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Unpiggable Pipelines – The Industry Wide Challenge

30 Jun

Industry research estimates that 40% of the world’s pipelines are difficult to pig, or otherwise deemed ‘unpiggable’. Unpiggable pipelines represent a significant challenge in the Oil and Gas Industry in relation to corrosion mitigation, flow assurance and inspection.

In many cases, there was no consideration given to the requirement for pigging at the pipeline design stage, or it was perhaps not deemed necessary based upon the understanding of fluid characteristics and/or operating conditions at the time. In some cases, pigging facilities may have been removed from the project scope due to budget constraints without due consideration given to the implications. In other cases, a pipeline may be designed to be piggable but subsequent pipeline damage, modifications or changes in operating conditions inhibit the ability to pig.

When operators are faced with unpiggable pipelines, it is generally necessary to address the following questions:

  • What is the requirement for pigging?
  • Why is the pipeline unpiggable?
  • Can the pipeline be made piggable?
  • How and when to Pig?
  • What are the alternatives to pigging?

AIE has extensive experience in helping operators answer these questions. With the use of our Veracity data analytics software, we are able to analyse and trend large volumes of operational and integrity data to support data driven decision making in the management of unpiggable pipelines.


The key drivers to pig a pipeline are generally to mitigate corrosion and flow assurance risks, or to perform Inline Inspection (ILI) using intelligent pigs. AIE can support the pipeline operator in understanding the requirement for pigging through various technical studies:

  • Pipeline risk assessment using Veracity Pipeline Module to identify and quantify the credible pipeline threats, and whether pigging is necessary to manage such threats.
  • Pipeline corrosion studies using Veracity CCM Module to quantify the threat of corrosion and determine any expected benefit from pigging.
  • Pipeline flow assurance studies to identify and quantify any flow assurance threats to the pipeline and propose recommendations for prevention and remediation.


Understanding the reason why a pipeline is not piggable is essential to identify and engineer an appropriate solution. AIE can perform a holistic review of the pipeline design, construction, and operational data to determine the piggability of the pipeline and hence identify any factors that would prevent pigging or pose a significant risk to a successful pig run. Concerns regarding pipeline piggability include but are not limited to the following:

  • No pig traps
  • Restricted access
  • Pipeline fittings (e.g. tees or wye)
  • Bore restrictions
  • Diameter or wall thickness changes
  • Operational conditions


Once the reasons for a pipeline being unpiggable are fully understood, a range of solutions can be identified to enable pipeline pigging and establish the technical and financial feasibility. These solutions may include:

  • Pipeline modification
  • Temporary piping and pig traps
  • Bidirectional pigging (e.g. using pumping spread or a ‘gas spring’)
  • Pig design modification
  • Use of non-conventional inspection technologies


Where the requirement and ability to pig a pipeline has been established, AIE can support the pipeline operator in developing a pigging program to ensure that the appropriate pigs are used and run at an optimal frequency, whilst also minimizing the potential for a stuck pig. AIE offers a range of operational support when it come to the planning and execution of pipeline pigging projects, including full project management service or discrete engineering scopes, including:

  • Pig design review
  • Development of pigging strategy (e.g. type and frequency)
  • Inspection technology review (e.g. based on types of defects expected)
  • Pigging risk assessments
  • Contingency planning
  • Development of maintenance requirements for pipeline facilities prior to pigging
  • Development of pigging procedures
  • Provision of on-site pigging SME support during pigging operations


Where technical or financial challenges remain, and pigging is deemed not to be feasible, AIE supports clients in the development of alternative strategies:

  • Development of corrosion control and monitoring KPIs using the AIE Veracity CCM software
  • Review of chemical selection to optimize corrosion control activities
  • Identification of flow assurance mitigation and monitoring options
  • Identification of alternative methods to establish pipeline integrity, including:
    • Internal Corrosion Direct Assessment (ICDA)
    • External Corrosion Direct Assessment (ECDA)
    • Alternative pipeline inspection strategies and technologies

If you would like to know more about the range of services we can offer to pipeline operators to overcome unpiggable pipeline challenges, please send us an inquiry using our website or email us at info@aiegroup.org.

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